The present invention relates to a thermal timer valve for the temperature-dependent operation of accessory devices of a mixture preparation system of a combustion engine.
Such a valve should operate as a function of time after the start of the engine, for example, to actuate the exhaust gas feedback system. There are known valves which, after a set heat-up time of an electric heating element, open or close the valve flow passage by the shift of a bimetal disk. There are also known valves which are placed, for example, in the cooling water cycle of the engine and shift after reaching a certain temperature. Sometimes, electrical auxiliary equipment must be avoided to relieve the vehicle electrical system. The valves located in the cooling water cycle might have an intolerably long response time at extreme outside temperatures. This object is achieved by a valve of the above type by providing a membrane space subject to intake pipe negative pressure, with the membrane being connected to a rod which is connected on one end to a valve closure and on the other end to a piston in an oil chamber.
The novel features which are considered as characteristic for the invention is set forth in particularly in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.